HYDRAULIC SYSTEMS CONTINUED
Charge Pressure Relief Valve Operation
Charge oil flows from the hydraulic oil filter through the passage (Figure 8, Item 1) to the passage (Figure 8, Item 9)
and then through the port (Figure 8, Item 8) to the poppet (Figure 8, Item 7). When the pressure against the poppet
overcomes the force of the spring (Figure 8, Item 3), the surface (Figure 8, Item 6) of the poppet moves to the left
and the poppet pushes the spring retainer (Figure 8, Item 5) against the force of the spring. Oil then flows past the
poppet into the spring chamber (Figure 8, Item 4) and then through the passage (Figure 8, Item 2) to the piston
pump's case drain. The poppet oscillates as the flow of the charge oil fluctuates in order to maintain a constant
pressure for the charge oil.
Figure 8. Charge Pressure Relief Valve.
The hydraulic oil filters are located behind the right-rear access door. The filters remove debris from the oil in order
to prevent damage to the hydraulic components. All of the oil from the charge pumps flows through the filters.
Filter (Figure 9, Item 3) filters the oil from the fan motor. The oil flows from the filter back to the left side hydrostatic
pump, which supplies the left drive loop. Filter (Figure 9, Item 1) filters the oil from the right side hydrostatic pump
charge pump. The oil flows from filter back to the right side hydrostatic pump, which supplies the right drive loop.
Filter (Figure 9, Item 2) filters oil for the winch. A bypass valve located in each oil filter base allows oil to bypass the
filters. This occurs if the oil is too cold to flow through the filters or if the filters are clogged. The oil filter bypass
indicator will light before the bypass valve opens.